Year	Number
1971	68.8241
1972	60.01655
1973	69.26267
1977	85.1
1978	84.43811
1979	87.45904
1981	81.45578
1982	68.62109
1983	55.97848
1984	56.51358
1985	61.52391
1986	60.72856
1987	61.65873
1988	56.03312
1989	57.56602
1990	54.53836
1991	54.74744
1992	53.37172
1993	54.80179
1994	57.74632
1995	57.59626
1998	60.87914
1999	61.4934
2000	63.98903
2001	65.94088
2002	67.24468
2004	65.23041
2005	66.33962
2006	67.26054
2007	64.79571
2008	63.99922
2009	61.28936
2010	58.48961
2011	55.41963
2012	54.84224
2013	54.92451
2014	54.83218
2015	54.66026
2016	53.60539
2017	52.43683
2018	55.27379